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State of Oregon 

Department of 

Environmental 

Quality 

NATIONAL POLLUTANT DISCHARGE 

ELIMINATION SYSTEM 

WASTE DISCHARGE PERMIT 

EVALUATION AND FACT SHEET 

April 2015 

Oregon Department of Environmental Quality 

Western Region 

4026 Fairview Industrial Dr. Salem OR 97302 

Permittee: 

Existing Permit 

Information: 

Source Contact: 

Source Location: 

LLID 

Receiving Stream 

Proposed Action: 

Source Category 

Permit Writer: 

Georgia-Pacific Consumer Products LP 

PO Box 215 

Halsey, OR 97348 

File Number: 105814 

Permit Number: 101488 

Expiration Date: November 30,2015 

EPA Reference Number: OR003340-5 

Alice McConaughy 

(541)369-1589 

30470 American Dr 

Halsey, OR 97348 

1227618456580-147.4-D 

Willamette River 

Permit Modification 

Application Number: 959327 

Date Received: January 13,2015 

NPDES Major - Industrial 

Steve Schnurbusch (503)378-8306 

Senior Water Quality Permitting Specialist 
Summary 

The Georgia Pacific Halsey Mill (GP) shares an outfall with neighboring Cascade Pacific Pulp 

(CPP). CPP owns the outfall and is planning to relocate the outfall about 1300 feet downstream 

from the existing outfall location. They are moving the outfall because a large gravel bar has 

formed immediately upstream from the current location and is preventing the effluent from 

rapidly mixing with the river. 

The new outfall is being moved to a deeper location in the river with higher stream velocities. 

The outfall will consist of a 100-foot multiport diffuser with 20 equally spaced diffusers. The 

combination of the new location with the diffuser design will promote rapid mixing of the 

effluent with the river. 

DEQ is proposing to modify the permit to incorporate the location of the new outfall. The permit 

modification is limited to two changes: 

1. The location of the outfall will change from river mile 147.7 to river mile 147.4. 

2. The length of the zone of initial dilution (ZID) will be reduced from 22 feet to 15 feet 

and the mixing zone length will be reduced from 300 feet to 40 feet. 

No other changes are being made to the permit. Comments regarding this permit modification 

are limited to the two changes listed above. 

Discussion 

The GP Halsey Mill is located just west of the town of Halsey. It sits adjacent to the Cascade 

Pacific Pulp mill. It consists of a paper mill, a converting operation, and a secondary fiber 

recycling plant with an activated sludge wastewater treatment system. The facility produces 

paper, which is converted into tissue and towels. The finished product is packaged and shipped 

for sale to commercial, retail and wholesale markets. The product mix and constituents vary 

based on customer and market demands. The facility is segregated into process buildings, which 

consist of the Paper Mill, Converting Area, Maintenance Area, Secondary Fiber and Wastewater 

Treatment. The effluent is combined with neighboring Cascade Pacific Pulp and currently is 

discharged to the Willamette River at river mile 147.7 through Cascade Pacific's outfall. 

GP Halsey is requesting their permit be modified to reflect changes to their outfall location. CPP 

owns the outfall and is proposing to move it downstream because of a gravel bar that has formed 

upstream of the existing outfall. Figure 1 shows an aerial photo of the river with the location and 

size of the gravel bar in 2006 compared to 2014. The gravel bar has increased in size and is now 

preventing the river from rapidly mixing with the effluent during low river flow conditions. The 

existing diffuser is a 104.5-foot multi-port diffuser with 19 operating ports. 

PAGE 2 
Figure 1: 2006 Aerial Photo and 2014 Aerial Photo (source: Google Earth) 

CPP hired a consultant consultant to perform a mixing zone study with the primary objective of 

finding a new outfall location to promote better mixing. Stream depth and velocity 

measurements were taken at various transects downstream of the existing outfall. This data is 

illustrated graphically in Figure 2. The figure clearly shows the low stream velocity at the 

existing diffuser location. The field study also indicated the river current at the existing location 

was swirling and eddy-like. Figure 2 indicates four alternate sites for the outfall. CPP chose site 

D to locate their new outfall (river mile 147.4). Site D was chosen because the river is deeper, 

experiences higher stream velocities and is 

well downstream from the influence of the 

gravel bar. 

The proposed diffuser is similar in length to 

the existing one. It is 100 feet long with 20 

duckbill ports equally spaced along the 

diffuser line. The ports are pointed 

downstream in a "fanned" orientation to 

optimize mixing (see Figure 3). The 

combined discharge of GP and CPP through 

the proposed diffuser was modeled using the 

mixing zone software CORMIXv9.0. The 

model predicts rapid mixing of the effluent 

immediately downstream of the diffuser. 

Because of the rapid mixing, DEQ is 

proposing to reduce the length of the ZID 

and the size of the mixing zone. The length 

is being reduced so that the dilution at the 

regulatory boundary (e.g. ZID) matches what 

was achieved with the existing diffuser as 

determined during the previous permit 

renewal. The existing diffuser achieved a 

dilution of about 47 at the ZID (22 feet 

downstream). The proposed diffuser 

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Figure 2: Bathymetry Field Study Data (Source: MixZon) 

PAGE 3 
Unidirectional Perpendicular Fanned-Out Design 

(H« lo Sols) 

Plan 

Viaw 

Ua (m/s) 

Side 

View 

Figure 3: Diffuser Orientation 

achieves a dilution of 47 at a distance of 15 feet 

downstream. DEQ is proposing to reduce the ZID 

from 22 feet to 15 feet. The existing diffuser 

achieved a dilution of about $5 at the edge of the 

300 foot mixing zone. The proposed diffuser 

achieves the same dilution at a distance of 40 feet 

downstream. DEQ is proposing to reduce the 

mixing zone distance from 300 feet to 40 feet. This 

greatly reduces the size of mixing zone and the area 

potentially impacted by the discharge. Moving the 

outfall downstream also prevents elevated effluent 

concentrations from occurring at the mouth of the 

slough just upstream from the existing outfall. 

Native fish have been documented in this slough as 

it provides good habitat for them. Moving the 

outfall downstream will ensure this critical habitat 

is not impacted by the discharge. Table 1 below lists 

dilution values for the various critical flow 

scenarios that are achieved by the diffuser. 

Table 1: Dilution Values 

\sute 

f ironic 

11 uman Health — 

II >n carcinogen 

11 uman Health -

carcinogen 

ZID 

Mixing Zone 

Mixing Zone 

Mixing Zone 

47 

85 

94 

193 

PAG E 4